The Impact of Exogenous Organic Matter on Wheat Growth and Mineral Nitrogen Availability in Soil

Round 1

Reviewer 1 Report

The manuscript is focused on the effect of exogenous organic matter and soil type on nitrogen availability in soil and wheat growth. Experimental studies, such as the one presented here, are certainly needed to found the most environmentally friendly farming methods. I appreciate the large amount of work that must have done into the experiment for this study. The data collection appears well thought out and designed.

However, I have some minor questions or recommendations:

Introduction:

This caption is clear and well written.

Methods:

L149: You write that you use mineral fertilization in the form of ammonia nitrate, but in Table 3 you write about Ca(NO₃)₂.

L154: Please, add the size of used pots.

L192: You write that you did correlation analyses (Pearson´s correlation), however there are no mentioned in the Results.

Results and discussion:

I recommend using in the whole text:

Nitrates and Ammonium or N-NO₃ and N-NH₄

Before sowing and after harvest (don´t use treatment with or without plants)

I recommend starting description of results with Table 4 (all sites) and then figure 2 where you show only site 2.

Tables:

Table 4 and 5: Use “Effect of soil type on ammonium nitrogen…” instead of “Differences…”, because I should assume that you show some calculated differences.

Table 5: One description of “Site-1 soil”, “Site-2 soil” and “Site-3 soil” is enough. Also order of EOMs in the table is different in comparison with Figs. 2,3 (see below).

Figures and Figure Captions:

Fig. 2 and 3: Add to the figures description “before sawing” and “after harvest”.

Fig. 3 caption: Change “…., lowercase letters indicate significant differences between the treatments separately for individual site….” if it is true.

Fig. 4: Please, check the legend of the figure. Is it wrong legend or the order of bars are different than in figures 2, 3? The order of bars in all figures must be the same.

Conclusions:

You mention that changes in nitrogen availability depend mainly on the soil physiochemical properties (pH, texture…). Can you be more specific and describe it according to your results?

Author Response

Reviewer 1

The manuscript is focused on the effect of exogenous organic matter and soil type on nitrogen availability in soil and wheat growth. Experimental studies, such as the one presented here, are certainly needed to found the most environmentally friendly farming methods. I appreciate the large amount of work that must have done into the experiment for this study. The data collection appears well thought out and designed.

However, I have some minor questions or recommendations:

Resp.: We would like to thank you for comments and suggestions, which contributed very much to improve our manuscript.  We have studied your comments carefully and have made corrections which we hope meet with approval. All suggestions and recommendations have been adopted, and the introduced changes are listed in the responses to the review.  

Introduction:

This caption is clear and well written.

Resp.: Thank you for your opinion.

Methods:

L149: You write that you use mineral fertilization in the form of ammonia nitrate, but in Table 3 you write about Ca(NO₃)₂.

Resp.: An appropriate corrections have been introduced into the text. We used calcium nitrate as mineral fertilizer.

L154: Please, add the size of used pots.

Resp.: We used 3.5 kg pots. The information has been introduced to the text.

L192: You write that you did correlation analyses (Pearson´s correlation), however there are no mentioned in the Results.

Resp.: An appropriate corrections have been introduced into the text.

Results and discussion:

I recommend using in the whole text: Nitrates and Ammonium or N-NO₃ and N-NH₄

Resp.: An appropriate corrections have been introduced into the text.

Before sowing and after harvest (don´t use treatment with or without plants)

Resp.: An appropriate corrections have been introduced into the text.

I recommend starting description of results with Table 4 (all sites) and then figure 2 where you show only site 2.

Resp.: As Reviewer suggested, we have changed the order of the discussed results (both, N-NO₃ and N-NH₄). An appropriate corrections have been introduced into the section 3.1.

Table 4 and 5: Use “Effect of soil type on ammonium nitrogen…” instead of “Differences…”, because I should assume that you show some calculated differences.

Table 5: One description of “Site-1 soil”, “Site-2 soil” and “Site-3 soil” is enough. Also order of EOMs in the table is different in comparison with Figs. 2,3 (see below).

Resp.: The table titles and the order of the variables have been changed according to suggestions.

Fig. 2 and 3: Add to the figures description “before sawing” and “after harvest”.

Resp.: An appropriate corrections have been introduced into the title of the Figure 2 and 3.

Fig. 3 caption: Change “…., lowercase letters indicate significant differences between the treatments separately for individual site….” if it is true.

Resp.: An appropriate corrections have been introduced into the captions in Figures 2, 3 and 4.

Fig. 4: Please, check the legend of the figure. Is it wrong legend or the order of bars are different than in figures 2, 3? The order of bars in all figures must be the same.

Resp.: The order of the bars has been changed. Legend has been adjusted to match previous figures.

Conclusions:

You mention that changes in nitrogen availability depend mainly on the soil physiochemical properties (pH, texture…). Can you be more specific and describe it according to your results?

Resp.: The relationship between soil properties and N availability has been specified in the conclusion text.

Reviewer 2 Report

The METODOLOGY of the study has some major faults.

• NH4-N content of the organic products applied was not analyzed, and to know this fraction is essential to estimate plant available N.
• I miss a real control without N application to see the real effect of each treatment including the control on soil ammonium and nitrate N contents and yield
• The material and methods lack some importaint details as size of the pots, way of measuring field capacity and field capacity value of each soil, treatment of the soil previius to the filling of the pots, number of plants per plot, etc.
• It is not clear when the organic fertilizer application was made, how long before the sowing? How were applied the EOMs? Were they mixed with the soils before filling the pots?
• The statistical design of the experiment is not detailed, and neither whay you consider and outlier.

RESULTS and DISCUSSION

• I think that the control was a treatment included in the ANOVA, but I cannot see letter indicating significant differences at the value of this treatment.
• Sometimes you comment differences among treatments profusely when the differences are not statistically significant. If the average values are similar according to the statistical analysis made, there is no point in comenting the differences.
• Some data from the table are repeated at the Figures. Data should not be shown twice.
• There are many explanations for the decrease in the nitrate soil content, but any of them is explained by the data shown. For example you talk about microorganisms, or N losses, but there is not any data showing values of microorganisms activity or N losses.
• Some differences among treatments are not properly discussed or explained, but sometimes you try to explain differences that are no significant.
• Consequently, the discussion is poor.

CONCLUSION

• To know if the application of organic fertilizers can replace mineral N fertilization obtaining the same yield, is neccesary to make field trials. The root system capacity to explore the soil to obtain not only N but also wáter cannot be estimated, and therefore it is very difficult to extract that kind of conclusions from pot experiments.
• Some conclusions are not supported by the data.

Comments for author File: Comments.pdf

Author Response

Reviewer 2

Resp.: We would like to thank you for comments and suggestions, which contributed very much to improve our manuscript.  We have studied your comments carefully and have made corrections which we hope meet with approval. All suggestions and recommendations have been adopted, and the introduced changes are listed in the responses to the review. 

The METODOLOGY of the study has some major faults.

• NH4-N content of the organic products applied was not analyzed, and to know this fraction is essential to estimate plant available N.

Resp.: Indeed the data on initial N-NH4 in organic materials was not provided. However, it must be emphasized that N-NH4 in the tested compost, as based on previous studies, is less than 1% of total N. This means that when equivalent of 140 kg N was applied as compost, only less than 1,4 kg was added as N-NH4. Such initial amount could not have any tremendous effect. In animal meal N exists mostly as proteins and other organic compounds, therefore undergoes mineralization processes before gest available to plants. Only in digestate ammonia content might be greater. Therefore we put major focus on N release in soil.

• I miss a real control without N application to see the real effect of each treatment including the control on soil ammonium and nitrate N contents and yield

Resp.: the aim was to compare effects of N added as EOM vs mineral nitrogen therefore we did not have a variant without any N fertilization. The result of such variant would be rather easy to predict – reduced yield. N is applied to soil every season so such conditions do not exist in reality.

• The material and methods lack some importaint details as size of the pots, way of measuring field capacity and field capacity value of each soil, treatment of the soil previius to the filling of the pots, number of plants per plot, etc.

Resp.: The detailed information has been added to the text in its methodological part.

• It is not clear when the organic fertilizer application was made, how long before the sowing? How were applied the EOMs? Were they mixed with the soils before filling the pots?

Resp.: The missing information has been added to the text in its methodological part.

• The statistical design of the experiment is not detailed, and neither whay you consider and outlier.

Resp.: More detailed information has been incorporated to the text. Statistical treatment. Including treatment of outliers, is now explained in the methodological part.

RESULTS and DISCUSSION

• I think that the control was a treatment included in the ANOVA, but I cannot see letter indicating significant differences at the value of this treatment.

Resp.: The table aims to present the differences between the effects of the same EOMs in different soils, while the figure shows the effects of different EOMs in the same soil – all differences have been marked with letters (upperletters-tables and lowerletters-Figures was applied for difference). Additional information has also been introduced into the ‘Statistics’ section.

• Sometimes you comment differences among treatments profusely when the differences are not statistically significant. If the average values are similar according to the statistical analysis made, there is no point in comenting the differences.

Resp.: The discussion has been substantially reworked.

• Some data from the table are repeated at the Figures. Data should not be shown twice.

Resp.: In fact figures and tables provide different information. Tables show differences between soils across the same soil amendment. Figures present differences within one soil.

• There are many explanations for the decrease in the nitrate soil content, but any of them is explained by the data shown. For example you talk about microorganisms, or N losses, but there is not any data showing values of microorganisms activity or N losses.

Resp.: Indeed we did not measure all parameters enabling detailed evaluation of full N cycle. For example, we did not measure gaseous losses of N which would require specific research infrastructure. Therefore some parts of discussion are based on assumptions and referring to literature. Measuring intensity of certain processes like nitrification, denitrification, or microbial diversity would be certainly helpful to some extent but they also, when using commonly applied protocols, are not able to provide strong explanations of the recorded N availability data.

• Some differences among treatments are not properly discussed or explained, but sometimes you try to explain differences that are no significant.
• Consequently, the discussion is poor.

 Resp.: The discussion has been improved in its several parts.

CONCLUSION

• To know if the application of organic fertilizers can replace mineral N fertilization obtaining the same yield, is neccesary to make field trials. The root system capacity to explore the soil to obtain not only N but also wáter cannot be estimated, and therefore it is very difficult to extract that kind of conclusions from pot experiments.

Resp.: We agree in principle, but both field and pot studies have advantages and limitations. We are aware of limitations, however greenhouse pot studies enable testing greater number of combinations, homogeneity of soils and EOM mixing with soil, precision and repeatability of moisture maintenance and rates of fertilizers, mitigate spatial diversity of soil in a field. 

• Some conclusions are not supported by the data.

Resp.: We went through the conclusions section and slightly reworked the text to be more specific. It contains conclusions referring to the study observations and needs for further research.

Reviewer 3 Report

This study evaluated soil NH4 and NO3-N dynamics and productivity of wheat in the pot experiment applying with mineral and organic fertilizer. soil NH4, NO3-N contents were different between soil types, while they were similar between fertilizer type in the same soil treatment. On the other hand, lower wheat production was found in the industrial compost treatment.

Effective use of organic fertilizer with reducing chemical fertilizer is urgent need in the agriculture. The manuscript is within the scope of journal.

 On the other hand, there are many unclear points in the materials and methods. In the results and discussion, mineralization of each organic matter basing on their properties (e.g. C/N ratio) and soil types was not well discussed. Therefore, need more improvement.

Introduction

Authors did not review relationship between type of soil and transformation of nitrogen in EOM.  

Materials and method

Some important information of the properties of the EOM and wheat growth conditions are not shown.

-Table 1: Please show nitrogen content (TN, NH4-N, NO3-N etc) of each soil.

-page 3, line 115-119: Soil is named by basing on soil properties (clay, sand, silt etc) not basing on site.

-page 4, line 36-39: What are the organic matter content and dry matter content in the digestate?

-page 4, line 26-27: Why did authors choose these EOM? These have any contrasting parameters such as C/N ratio to be compared?

-Table 2: Please show available N content and C/N ratio of each EOM in Table 2.

-page 4, line 148: Why did authors choose these nitrogen rate?

-page 4, line 149-150: In the control, did author apply only nitrogen? How about other nutrient such as K and P?

-page 5, line 154: Please show detailed pot information. For example, hole for drainage at the bottom, size of pot, amount of soil in the pot, bulk density of the soil in each pot.

-page 5, line 157-158: Where were these pot grown, outside or inside? What was the growth conditions, such as air temperature and humidity etc?

-page 5, line 161: How did author take soil sample? And how long did it take until taking soil sample for before the growing season from preparing pot?

Results and discussion

Authors found different NO3-N dynamics between different soil. However, these reason was not so discussed basing on soil properties.

-Figure 2 and Table 1: It looks that same data (NH4-N in site 2 soil) are shown in Fig 2 and Table 1. Therefore, I recommend to delete Fig. 2 and show only Table 4 to explain NH4-N.

-page 6, line 201-202: Values (83.6, 11.5 and 69 g/kg) are in those in Table 2? Please clarify.

-page 6, line 212: Statistics analysis in Table 4 looks to compare between soil types, not before seeding and after harvest.

-page 6, line 214-216: Any evidence for ammonia volatilization?

-page 7, line 237-240: Please discuss mineralization and nitrification were already occurred or not when taking the sample for Fig .3a.

-page 7, line 239-240: What is a mechanism for higher NO3-N content in clay rich soil? Did author take into account initial NO3-N content of the soil in this discussion?

-page 7, line 240-241: Did author take into account NO3-N content in the soil and EOM on contribution of NO3-N content before the growing season?

-page 7, line 257-258: For which soil?

-page 9, line 280-282: Differences of what? Please clarify.

-page 9, line 284-285: Authors have data of amount of nitrogen in the harvested wheat for the evidence of this description?

-page 9, line 298-300: Please discuss relation between mineralization of each EOMs and their C/N ratio.

-page 11, line 381-382: How do author consider about deficiency of nutrient other than N in industrial compost treatments? For example, P content in industrial compost is much lower than that in other EOM.

Conclusion

-page 12, line 404-406: In the results and discussion, it looks that how soil properties affect nitrogen transformation was not so discussed.

Author Response

Reviewer 3

This study evaluated soil NH4 and NO3-N dynamics and productivity of wheat in the pot experiment applying with mineral and organic fertilizer. soil NH4, NO3-N contents were different between soil types, while they were similar between fertilizer type in the same soil treatment. On the other hand, lower wheat production was found in the industrial compost treatment.

Effective use of organic fertilizer with reducing chemical fertilizer is urgent need in the agriculture. The manuscript is within the scope of journal.

 On the other hand, there are many unclear points in the materials and methods. In the results and discussion, mineralization of each organic matter basing on their properties (e.g. C/N ratio) and soil types was not well discussed. Therefore, need more improvement.

Resp.: We would like to thank you for comments and suggestions, which contributed very much to improve our manuscript.  We have studied your comments carefully and have made corrections which we hope meet with approval. All suggestions and recommendations have been adopted, and the introduced changes are listed in the responses to the review. 

Introduction

Authors did not review relationship between type of soil and transformation of nitrogen in EOM.  

Resp.: The introduction has been expanded in some paragraphs by following statements:

“Organic matter derived from these materials is characterized by various properties (decomposition rate, availability of nutrients, sorption properties) due to different formation processes and the diversity of the feedstock materials. Therefore, their persistence and impact on the N availability are diversified”

“Addition of EOMs enhances hydrolysable and non-hydrolysable N contents in soil. Chakraborty et al. (2012) established that total hydrolysable N status declined with application of inorganic N fertilizer alone and increased with conjunctive use of inorganic N fertilizer and manures. Application of EOMs in different stage of decomposability not only affects pattern of N availability but also influences the distribution of their N-NH4- and N-NO3+ forms in soils (Beraud er. al., 2005). The main difference in EOMs efficiency of nitrogen input into the soil results from their total C and N content. Nevertheless, the transformation of organic and inorganic nitrogen in soil is mainly governed by physico-chemical and biological properties of soil.”

The influence of some properties of soils (clay content, pH) and microorganisms was emphasized in the discussion with relation to the described results.

“The limited availability of N-NH4+ ammonium ions in soils before planting sowing most likely resulted from their partial binding to the soil sorption complex of especially clay minerals () or its rapid transformation into N-NO3- through nitrification process. Moreover, the nitrogen could be moved by leaching or can escape into the atmosphere through gaseous loss (denitrification). Brady and Weil (2010) suggested that understanding the basic nitrogen cycle provides insight into plant nutrient relationships and can provide the basis of nutrient management decisions. “

“The lowest N-NO3- content in Site-2 soil can be attributed to most intensive N-NO3- acquisition by wheat and less intensive transformation of N-NH4+ to N-NO3- through nitrification process at the lowest pH. The latter hypothesis is supported by the observed highest ammonia content in Site-2 soil. Nagele and Conrad (1990) observed that the release of nitrogen increased after fertilization and strongly decreased with increasing pHof acidic soil adjusted to 6.5. Authors suggested that soil pH exerts complex controls, e.g., on microbial populations or enzyme activities involved in nitrification and denitrification. Neina (2019) stated that mineralization and the degradation occurs mainly in soils with pH between 6.5 and 8.”

“Nitrogen supplied to the soil by different type of EOMs occurs mainly in organic complexes as N-NH4+ . During organic matter decomposition, N-NH4+ is released into the soil and converted to N-NO3- nitrates by nitrification processes caused by different groups of microorganisms (Mondini et al. 2008; Amlinger et al. 2003]. Ammonium ions not immobilized or taken up by higher plants are usually converted rapidly to NO₃⁻ ions. This is a two-step process, during which bacteria (Nitrosomonas) convert NH₄⁺ to nitrite (NO₂⁻), and then other bacteria (Nitrobacter), convert the NO₂⁻ to NO₃⁻ [20, 26]. This process requires a well-aerated soil and occurs rapidly enough that one usually finds mostly NO₃⁻ rather than NH₄⁺ in soils during the growing season (Amlinger et al. 2003; García-Ruiz et al. 2008).”

Materials and method

Some important information of the properties of the EOM and wheat growth conditions are not shown.

-Table 1: Please show nitrogen content (TN, NH4-N, NO3-N etc) of each soil.

Resp.: The total content of N in soils has been added  to table 2. We measured initial extractable N-NH4 and N-NO3 in soils but they were not presented in text since the contents were very low and their effect was fully mitigated by substantial amounts of nitrogen introduced via EOM or Ca-nitrate application.  

-page 3, line 115-119: Soil is named by basing on soil properties (clay, sand, silt etc) not basing on site.

Resp.: Both sampling location and texture are provided in the description of soils

-page 4, line 36-39: What are the organic matter content and dry matter content in the digestate?

Resp.: The missing information has been added.

-page 4, line 26-27: Why did authors choose these EOM? These have any contrasting parameters such as C/N ratio to be compared?

Resp.: We aimed at comparing EOMs derived from fully different technological processes: composting, fermentation and bone grounding and diverse substrates. We also selected EOMs available in practical scale in the region. Studying C/N ration effect was not a major question to be answered. To study this we would have to compare various composts with different C/N ratio. This was a goal of another study we have  recently performed.

-Table 2: Please show available N content and C/N ratio of each EOM in Table 2.

Resp.: C/N ratio has been added to the table. We did not measure available N in EOMs.

-page 4, line 148: Why did authors choose these nitrogen rate?

Resp.: The maximum permissible rate of N applied as manure is 170 kg/ha. Since the soils were diverse, including one sandy soil, the rate applied as organic amendments was reduced to equivalent of 140 kg/ha. It is also in agreement with the recommended rate of N for spring wheat which is around 140 hg/ha. In response to the study goals we tested impact of N applied fully as EOM and as a mixture of mineral form and EOM

-page 4, line 149-150: In the control, did author apply only nitrogen? How about other nutrient such as K and P?

Resp.: We did not apply additional K and P not to interfere with EOM effects. As we measured, the initial levels of available P and K in soils were sufficient, since the soils were collected from regularly fertilized fields.

-page 5, line 154: Please show detailed pot information. For example, hole for drainage at the bottom, size of pot, amount of soil in the pot, bulk density of the soil in each pot.

Resp.: More detailed information has been provided in the text.

-page 5, line 157-158: Where were these pot grown, outside or inside? What was the growth conditions, such as air temperature and humidity etc?

Resp.: The study was run in greenhouse – the details have been added to the text

-page 5, line 161: How did author take soil sample? And how long did it take until taking soil sample for before the growing season from preparing pot?

Resp.: The information has been added to the text on the description of the study. Soil samples were taken 4 weeks after mixing soils with EOMs (time to let EOM react with soil) and then after harvest. Soils were taken out of pots, homogenized in plastic bag and then sample was collected.

Results and discussion

Authors found different NO3-N dynamics between different soil. However, these reason was not so discussed basing on soil properties.

Resp.: The discussion have been expanded in this issue in several paragraphs of manuscript.

-Figure 2 and Table 1: It looks that same data (NH4-N in site 2 soil) are shown in Fig 2 and Table 1. Therefore, I recommend to delete Fig. 2 and show only Table 4 to explain NH4-N.

Resp.: Table 1 shows selected physical and chemical properties of the soil material used in the experiment while Figure 2 relates to the results. Perhaps your suggestion referred to Table 4. The table aims to present the differences between the effects of the same EOMs in different soils, while the figure shows the effects of different EOMs in the same soil – all differences have been marked with letters (upperletters-tables and lowerletters-Figures was applied for difference). Additional information has also been introduced into the ‘Statistics’ section.

-page 6, line 201-202: Values (83.6, 11.5 and 69 g/kg) are in those in Table 2? Please clarify.

Resp.: The given values refer to Table 2. Appropriate changes have been introduced.

-page 6, line 212: Statistics analysis in Table 4 looks to compare between soil types, not before seeding and after harvest.

Resp.: The given values refer to Table 2. Appropriate changes have been introduced.

-page 6, line 214-216: Any evidence for ammonia volatilization?

Resp.: Unfortunately not. We have not conducted studies on nitrogen volatilization from soil. These are only assumptions based on the available literature data.

-page 7, line 237-240: Please discuss mineralization and nitrification were already occurred or not when taking the sample for Fig .3a.

Resp.: A text hypothesizing reasons of low N-NH4 shortly after soil amendment has been added to the text. Relatively slow mineralization and intensive nitrification are potential explanations.

-page 7, line 239-240: What is a mechanism for higher NO3-N content in clay rich soil? Did author take into account initial NO3-N content of the soil in this discussion?

Resp.: The mechanism is not clear therefore it was not explained. Initial content of N-NO3 in all soils was low: < 5 mg/kg that could not have affected its level after fertilizer and EOM addition.

-page 7, line 240-241: Did author take into account NO3-N content in the soil and EOM on contribution of NO3-N content before the growing season?

Resp.: As noted above, the initial content of N-NO3 in all soils was low: < 5 mg/kg that could not have substantially affected its level after fertilizer and EOM addition. We did not measure initial N-NO3 in EOMs. Inconsistency between N-NO3 levels after addition of a given EOM in different soils shows that initial N-NO3 was not a major factor but it was rather interaction between EOM type and soil type.

-page 7, line 257-258: For which soil?

Resp.: This statement regarded for Site-2 soil and Site-3 soil. Appropriate changes have been introduced.

-page 9, line 280-282: Differences of what? Please clarify.

Resp.: The sentence has been reworded. “The influence of soil properties (Site-1 soil vs Site-2 soil vs Site-3 soil) on the effectiveness of EOM application was  observed in the case of industrial compost fertilization at 100% rate and digestate at 50% rate.”

-page 9, line 284-285: Authors have data of amount of nitrogen in the harvested wheat for the evidence of this description?

Resp.: Unfortunately, we did not conduct such analyzes. We measured the yield on the basis of the weight of the plant and grain.

-page 9, line 298-300: Please discuss relation between mineralization of each EOMs and their C/N ratio.

Resp.: The following sentences have been introduced: “Organic amendments selected for our study differed in the quality of organic matter expressed by the carbon to nitrogen ratio. The highest C:N parameter (C:N=7.8) was noted for industrial compost while the lower for digestate (C:N=5.9) and animal meal (C:N=4.8). These relations reflected only availability of noted N-NO₃^- and N-NH₄⁺concentrations. Janssen (1996) indicated that mineralization of organic amendments is mainly related with the microbial conversion of the organic matter. Thus, part of the nitrogen that is present in the converted organic material is used by microorganisms and part is released (mineralized) as inorganic nitrogen. If the converted organic matter is characterized by a low nitrogen content (high C: N ratio) the amount of nitrogen that can be converted may be too low, nitrogen deficiencies for microorganisms may occur, resulting in a secondary uptake of inorganic nitrogen and their immobilization for plants.”

-page 11, line 381-382: How do author consider about deficiency of nutrient other than N in industrial compost treatments? For example, P content in industrial compost is much lower than that in other EOM.

Resp.: No visible symptoms of any deficiency were observed. Soils used in the experiment were collected from regularly fertilized fields. As it is commonly known, substantial part of P applied in fertilizers remains in soil after harvest. Therefore we do ntt assume any nutrient deficiencies. Analysis of P availability in bulk soils before the study revealed moderate to high availability of P.

 Conclusion

-page 12, line 404-406: In the results and discussion, it looks that how soil properties affect nitrogen transformation was not so discussed.

Resp.: The relationship between soil properties and N availability has been specified in the conclusion text.

Reviewer 4 Report

Dear authors,

Your article is very interesting, but in some places you need to edit or justify your reasons.

line 12. The abstract needs to be shortened.

line 44. Introduction could be shortened.

lines 64.-66. you mix different organic matter and the way organic matter is formed - it is unclear

line 117. What are these different agroecological habitats? What are they differ in?

line 121. Figure 1- better localization within Europe

line 123. Table 1- Why isn't N and other nutrients determined? Why it is something in the line Dlouha Ves bold?

line 144. Table 2- Is this nutrient content calculated to dry matter? Why it is something in the line Animal meal bold?

line 148. Why the dose 140 kg ha-1 was chosen? NH₄NO₃  or Ca(NO₃)₂? If 

Ca(NO₃)₂ how do you justify the different addition of Ca?

line 152. Please indicate the amount of org. matter added per ha (pot). I do not understand when comparing the effect of organic matter, why it is always added according to the N content. Can you explain it please?

line 156- how many kg of soil is in 1 pot? In each variant the amount of soil was the same and the addition of org. matter was different?

line 161-Which sampling procedure - how many repetitons per a pot/variant?

line 195- Which statictical method was used to discriminate and determine outliners?

line 198- I lack more discussion with the available literature on the topic.

line 202- Is it correct 11.5 g kg^-1? In the Table 2 authors show N content of Industrial compost 23 g kg^-1. I don't understand why table 3- you mean table 2?

line 219. I do not find this display useful - what was the standard deviation value of the control? Much more better is that control is one variant of experiment with SD.

line 221. Figure 2- in table 4 you state the letters b, here a- I do not understand this statistic, figure 2 duplicates the table

line 225. Despite the units are mentioned in the text, the table should contain this information.

lines 231-233. Too short results and discussion of N-NH4+, Figure 3 and Table 5 should be moved upside in front of this part of text.

line 260. Error in the description on the x-axis. Statistical differences expressed as letters are not corresponding between the Figure 3 and Table 5.

line 262. Statistical differences expressed as letters are not corresponding between the Figure 3 and Table 5.

line 270. Without the standard deviation value of the control, the statistical differences between variants and control are unclear. Moreover - the information of Figure 3 and Table 5 is redundant.

line 287. If this conclusion can by compared to the published observations by other authors.

line 292. Too speculative without an evidence for this statement. Or you were measure microbial biomass?

lines 309-312. bad numbers of references

line 373. Are letters (a,b,c,d) in table 5 correct?

Thank you and looking forward to your feedback.

Author Response

Reviewer 4

Your article is very interesting, but in some places you need to edit or justify your reasons.

Resp.: We would like to thank you for comments and suggestions, which contributed very much to improve our manuscript.  We have studied your comments carefully and have made corrections which we hope meet with approval. All suggestions and recommendations have been adopted, and the introduced changes are listed in the responses to the review. 

line 12. The abstract needs to be shortened.

Resp.: Some redundant sentences have been removed from the abstract.

line 44. Introduction could be shortened.

Resp.: Some redundant sentences have been removed from the introduction.

lines 64.-66. you mix different organic matter and the way organic matter is formed - it is unclear

Resp.: Additional sentence has been added: “Organic matter derived from these materials is characterized by various properties (decomposition rate, availability of nutrients, sorption properties) due to different formation processes and the diversity of the feedstock materials. Therefore, their persistence and impact on the soil environment are diversified”.

The addition of EOMs of various origins to soils was used for evaluation of their potential effect on nitrogen release. Therefore the organic matter formation processes in individual materials applied in our investigation were not of key importance. One of the additional objectives of this research was to analysis of alternative nitrogen sources derived from waste materials that could be used in agriculture.

line 117. What are these different agroecological habitats? What are they differ in?

Resp.: the term of "agroecological habitats" was used to emphasize that the soils were sampled from the areas of arable lands on which various interrelationships between living organisms - vegetation - soil type were marked, and that agrotechnical treatments may had a significant impact on these interdependencies.

line 121. Figure 1- better localization within Europe

Resp.: We rather suggest to show detailed location of sampling points in the transboundary region. Positioning the locations in Europe would cost resolution of the map.

line 123. Table 1- Why isn't N and other nutrients determined? Why it is something in the line Dlouha Ves bold?

Resp.: Total N has been added to the table. Since other nutrients as available P, K, Mg were not deficient in these regularly fertilized soils, we did not focus on them. 

line 144. Table 2- Is this nutrient content calculated to dry matter? Why it is something in the line Animal meal bold?

Resp.: all analyzed physico-chemical properties summarized in the Table 1 and 2 are expressed on a dry matter.

line 148. Why the dose 140 kg ha-1 was chosen? NH₄NO₃  or Ca(NO₃)₂? If  Ca(NO₃)₂ how do you justify the different addition of Ca?

Resp.: The maximum permissible rate of N applied as manure is 170 kg/ha. Since the soils were diverse, including one sandy soil, the rate applied as organic amendments was reduced to equivalent of 140 kg/ha. It is also in agreement with the recommended rate of N for spring wheat which is around 140 hg/ha. Mineral N was added as C-nitrate. We did not add additional Ca when EOMs were applied since we assumed sufficient Ca levels in soil, especially in those with neutral pH. Ca is also contained in EOMs to some extent.

line 152. Please indicate the amount of org. matter added per ha (pot). I do not understand when comparing the effect of organic matter, why it is always added according to the N content. Can you explain it please?

Resp.: The amount of EOMs added to the pot did not exceed 25 g (25 g in case of digestate, 17 g in case compost and 3.3 g for animal meal. We designed the rates of EOMs based on amount of N to be applied. Therefore the total amount of EOMs or amount of added organic matter were different. The goal of the study was to assess impact of various N forms and sources on its dynamics in soil plus effect of N source on crop yields. We wanted to test how mineral N fertilization can be replaced with its organic sources. To be able to evaluate this we had to provide similar amounts of N in soil amendments. Besides this, agricultural good practice in applying organic fertilizers refers to rate of N. Organic matter itself does not generate risks, as opposite to N excessive amounts. If we performed a study on water retention we would have applied EOMs on OM basis. We believe that in a study aimed at N dynamics, referring to N rate was appropriate. Applying the same OM amounts would result in dramatically different N rates between combinations, that would not allow to reach the study objectives.

line 156- how many kg of soil is in 1 pot? In each variant the amount of soil was the same and the addition of org. matter was different?

Resp.: It was 3.5 kg of soil in each pot. Yes, in each variant weight of soil was the same. The volume of EOM was different for each EOM. We reflected the situation existing in practice – when EOMs are applied in the field the overall volume of sol is increased. More details on the pot experiment were added to the text.

line 161-Which sampling procedure - how many repetitons per a pot/variant?

Resp.: A four repetitions of each combination were applied. Soil sampling was performed through mixing soil in a plastic bag to reach homogeneity of soil. Some details has been added to the text.

line 195- Which statistical method was used to discriminate and determine outliners?

Resp.: The chi-square test was used to assess the relationship between the frequency distribution of responses in the variable within one combination performed in repetitions to eliminate the spurious or random error effect. This test was used in the analysis of nominal variables. The elimination of outliers in the results maintains the traceability.

line 198- I lack more discussion with the available literature on the topic.

Resp.: The discussion has been completed and expanded in some paragraphs.

line 202- Is it correct 11.5 g kg^-1? In the Table 2 authors show N content of Industrial compost 23 g kg^-1. I don't understand why table 3- you mean table 2?

Resp.: The mistake has been corrected. The discussed values are included in the Table 2.

line 219. I do not find this display useful - what was the standard deviation value of the control? Much more better is that control is one variant of experiment with SD.

Resp.: The control value has been added to the charts as a one of the variable.

line 221. Figure 2- in table 4 you state the letters b, here a- I do not understand this statistic, figure 2 duplicates the table

Resp.: The letters in the figures indicate the differences between the EOM amendments impact in individual soil while the letters in the table indicate the differences between the soils (Site-1 soil, Site-2 soil, Site-3 soil) with the same EOM amendment.. To denote differences, the letters were changed to lowercase (Figures) and uppercase (Tables). The letters indicate significant differences based on the Tukey’s test.

line 225. Despite the units are mentioned in the text, the table should contain this information.

Resp.: The missing data in the tables were supplemented.

lines 231-233. Too short results and discussion of N-NH4+, Figure 3 and Table 5 should be moved upside in front of this part of text.

Resp.: Figure 3 and Table 5 have been moved upside in front of the text, but the journal editorial office arranges figures and tables according to its own template. The discussion and description of the results have been expanded.

line 260. Error in the description on the x-axis. Statistical differences expressed as letters are not corresponding between the Figure 3 and Table 5.

Resp.: The mistake in the description of the axis has been corrected. Statistical differences expressed by the letters in the table and figures do not match because they indicate other differences. The letters in the figures indicate the differences between the EOM amendments impact in individual soil while the letters in the table indicate the differences between the soils (Site-1 soil, Site-2 soil, Site-3 soil) with the same EOM amendment. For clarity, the letters were differentiated and additional detailed description was added in the statistics section.

line 270. Without the standard deviation value of the control, the statistical differences between variants and control are unclear. Moreover - the information of Figure 3 and Table 5 is redundant.

Resp.: The control has been added to the charts as a variable, which change the readability of the results.

line 287. If this conclusion can by compared to the published observations by other authors.

Resp.: We supported this statements by research of other authors “Nagele and Conrad (1990) observed that the release of nitrogen increased after fertilization and strongly decreased with increasing pH of acidic soil adjusted to 6.5. Authors suggested that soil pH exerts complex controls, e.g., on microbial populations or enzyme activities involved in nitrification and denitrification”. Moreover, Neina (2019) stated that mineralization and the degradation occurs mainly in soils with pH between 6.5 and 8.”

line 292. Too speculative without an evidence for this statement. Or you were measure microbial biomass?

Resp.: This assumption has been removed from the text..

lines 309-312. bad numbers of references

Resp.: The mistake has been corrected.

line 373. Are letters (a,b,c,d) in table 5 correct?

Resp.: Yes, they are - Letters denote individual groups of variables. If their confidence intervals "overlap" this indicate a  statistically insignificant difference and cause the creating groups marked with several letters.

Thank you and looking forward to your feedback.

Resp.: Thank you very much for your review. We hope that introduced changes into the manuscript significantly improved our paper.

Round 2

Reviewer 2 Report

MATERIALS AND METHODS

Even if in this new version some details about the experiment have been better explained, there are some faults that cannot be improved and other as the statistical design that has not been detailed :

• The statistical design of the experiment is not detailed. Is it a randomized complete block design ? You don’t specify the number of factors you are analyzing. I guess you have two factors : EOM and moment. So you should analyze the interactions between the two factors. You should know the design of the experiment before doing the ANOVA.

RESULTS and DISCUSSION

A great part of the comments made at this section have not been taken into account in the new article. These are the most important ones.

• Some data from the table are repeated at the Figures. Data should not be shown twice.

Resp.: In fact figures and tables provide different information. Tables show differences between soils across the same soil amendment. Figures present differences within one soil.

But you have the same means for Soil Site 2 in the figure and in the table. Ir you use only the table and writte two type of letters (capital and lower case for example) to differentiate among means you can study differences between soils across the same soil amendment and differentes among EOMs inside each type of soil.

• Sometimes you comment differences among treatments profusely when the differences are not statistically significant. If the average values are similar according to the statistical analysis made, there is no point in comenting the differences.
• There are many explanations for the decrease in the nitrate soil content, but any of them is explained by the data shown. For example you talk about microorganisms, enzymatic activities or N losses, but there is not any data showing values of microorganisms activity or N losses. You comment also that « The limited availability of ammonium ions in soils before planting most likely resulted from 229 their partial binding to the soil sorption complex of especially clay minerals », but you have not measured that.

Resp.: Indeed we did not measure all parameters enabling detailed evaluation of full N cycle. For example, we did not measure gaseous losses of N which would require specific research infrastructure. Therefore some parts of discussion are based on assumptions and referring to literature. Measuring intensity of certain processes like nitrification, denitrification, or microbial diversity would be certainly helpful to some extent but they also, when using commonly applied protocols, are not able to provide strong explanations of the recorded N availability data.

Some authors measured intensity of certain processes before, because if anyone did that in the past we could not explain or make assumptions based on literature. I can understand that may be you don’t have to measure everything, but in this case the discussion is based enterely in assumptions.

• Some differences among treatments are not properly discussed or explained, but sometimes you try to explain differences that are no significant.

For example Why do you think there are differences in soil nitrate content for the different EOM?. There is a significant difference that is not discussed properly

• The result and discussion setion has improved, but in muy opinion is still poor.

CONCLUSION

• Even if this kind of experiments can help us to understand what is going on in the field, because we can measure more variables and in an intensive way, and control all the external factors of variance, we cannot assume that the influence on yield of the treatments will be the same in the field. In this sense, I agree with you that both field and pot studies have advantages and limitations. We are aware of limitations, however greenhouse pot studies enable testing greater number of combinations, homogeneity of soils and EOM mixing with soil, precision and repeatability of moisture maintenance and rates of fertilizers, mitigate spatial diversity of soil in a field. 
• Much weight of the conclusions is put in the yield, and I don't think you can give recommendations based on the yields obtained in this kind of experiments. It is important to measure yield, but more to understand the mineralization process and how it is influenced by the plants and by its N uptake.
• To know if the application of organic fertilizers can replace mineral N fertilization obtaining the same yield, is neccesary to make field trials. The root system capacity to explore the soil to obtain not only N but also wáter cannot be estimated, and therefore it is very difficult to extract that kind of conclusions from pot experiments. Besides surely the yield potential, and consequently the N neccesities are higher.

Also the pdf article with the new comments.

Comments for author File: Comments.pdf

Author Response

Response to Reviewer 2

We would like to thank you for comments and suggestions. We have studied your comments carefully and have made corrections which we hope meet with approval. All suggestions and recommendations have been adopted, and the introduced changes are listed in the responses to the review. Moreover linguistic and grammatical errors have been corrected by the MDPI English Proofreading Service.

MATERIALS AND METHODS

Even if in this new version some details about the experiment have been better explained, there are some faults that cannot be improved and other as the statistical design that has not been detailed :

• The statistical design of the experiment is not detailed. Is it a randomized complete block design ? You don’t specify the number of factors you are analyzing. I guess you have two factors : EOM and moment. So you should analyze the interactions between the two factors. You should know the design of the experiment before doing the ANOVA.

Resp.2: Unfortunately, we do not agree with the Reviewer. The experimental design is described in detail, including the fertilizer combinations tested that are presented in Table 3.  The “moment” (sampling time) was not the experimental factor, because the nitrogen content was measured in the soil after the harvest while the pre-harvest analysis of soil was a kind of starting point.  We refer to this point in the discussion.

RESULTS and DISCUSSION

A great part of the comments made at this section have not been taken into account in the new article. These are the most important ones.

• Some data from the table are repeated at the Figures. Data should not be shown twice.

Resp.2: In fact figures and tables provide different information. Tables show differences between soils across the same soil amendment. Figures present differences within one soil.

• But you have the same means for Soil Site 2 in the figure and in the table. Ir you use only the table and writte two type of letters (capital and lower case for example) to differentiate among means you can study differences between soils across the same soil amendment and differentes among EOMs inside each type of soil.

Resp. 2: We tried to introduce into the manuscript all comments included in your review. According to our previous answer the table aims to present the differences between the effects of the same EOMs in different soils, while the figure shows the effects of different EOMs in the same soil – all differences have been marked with letters (upperletters-tables and lowerletters-figures were applied for difference). Based on this, the data presented in the table and in the figure reflect the impact of other factors. Additional information has also been introduced into the ‘Statistics’ section. Of course, we can include everything in one table, but it would be more extensive and "heavier" to understand for the common reader. We believe that clearly presented results in the form of tables (numerical data) and in the form of a graph (visual data) are much better perceived and the differences distinguished.

• Sometimes you comment differences among treatments profusely when the differences are not statistically significant. If the average values are similar according to the statistical analysis made, there is no point in comenting the differences.
• There are many explanations for the decrease in the nitrate soil content, but any of them is explained by the data shown. For example you talk about microorganisms, enzymatic activities or N losses, but there is not any data showing values of microorganisms activity or N losses. You comment also that « The limited availability of ammonium ions in soils before planting most likely resulted from 229 their partial binding to the soil sorption complex of especially clay minerals », but you have not measured that.

Resp.2: Indeed we did not measure all parameters enabling detailed evaluation of full N cycle. For example, we did not measure gaseous losses of N which would require specific research infrastructure. Therefore some parts of discussion are based on assumptions and referring to literature. Measuring intensity of certain processes like nitrification, denitrification, or microbial diversity would be certainly helpful to some extent but they also, when using commonly applied protocols, are not able to provide strong explanations of the recorded N availability data.

Some authors measured intensity of certain processes before, because if anyone did that in the past we could not explain or make assumptions based on literature. I can understand that may be you don’t have to measure everything, but in this case the discussion is based enterely in assumptions.

Resp. 2: Due to the fact that our paper refers to the analysis of the EOMs impact on mineral nitrogen content - not its pathways in soil, some observations were discussed on the basis of available literature data. Our goal was to study mineral N dynamics and contents after application of particular organic materials. We think that this is an advantage of our manuscript due to detailed and genuine scientific discussion related with potential assessment of the observed results and its comparing with data published by other authors.

• Some differences among treatments are not properly discussed or explained, but sometimes you try to explain differences that are no significant.

Resp. 2: Unfortunately, due to the overly general suggestion regarding "some differences", we don't know how we can improve our manuscript in this issue. We tried to discuss in detail all observed differences or similarities in the effect of EOMs addition on nitrogen content. Indeed, some differences may not be statistically significant (which would probably be verified on a larger population of results) but from a scientific point of view we found it appropriate to briefly mention these trends. However it is clear in the text which differences are statistically significant.

For example Why do you think there are differences in soil nitrate content for the different EOM?. There is a significant difference that is not discussed properly

Resp. 2: It seems to us that the observed differences are caused by the efficiency of N uptake from soils with different properties by the test plants and the nitrogen forms (solid ---> dissolved and high molecular weight ---> low molecular weight) in the applied EOMs. We expanded these points in the discussion.

CONCLUSION

• Even if this kind of experiments can help us to understand what is going on in the field, because we can measure more variables and in an intensive way, and control all the external factors of variance, we cannot assume that the influence on yield of the treatments will be the same in the field. In this sense, I agree with you that both field and pot studies have advantages and limitations. We are aware of limitations, however greenhouse pot studies enable testing greater number of combinations, homogeneity of soils and EOM mixing with soil, precision and repeatability of moisture maintenance and rates of fertilizers, mitigate spatial diversity of soil in a field. 

Resp. 2 : Pot experiment as the first stage before field experiments constitutes very important "step" due to the easier possibility of controlling established factors with simultaneous observation the processes in a smaller scale. The described research was the first step in a broader assessment of EOMs on soil properties and the availability of nutrients for crop plants.

• Much weight of the conclusions is put in the yield, and I don't think you can give recommendations based on the yields obtained in this kind of experiments. It is important to measure yield, but more to understand the mineralization process and how it is influenced by the plants and by its N uptake.

Resp. 2: Some sentences in the conclusions have been changed according to your suggestion.

• To know if the application of organic fertilizers can replace mineral N fertilization obtaining the same yield, is neccesary to make field trials. The root system capacity to explore the soil to obtain not only N but also wáter cannot be estimated, and therefore it is very difficult to extract that kind of conclusions from pot experiments. Besides surely the yield potential, and consequently the N neccesities are higher.

Resp. 2: We agree with you, but the conclusions are related to the results of pot experiment. We do not draw any conclusions referring to field effects of EOM application.  Of course the effect of EOMs should be verified in subsequent field experiment and we have such a statement in the Conclusions section

Also the pdf article with the new comments.

Resp. 2: We introduced the changes into the manuscript.

Reviewer 3 Report

The authors adequately addressed my comments and improved their manuscript.

Author Response

We would like to thank you for comments and suggestions, which contributed very much to improve our manuscript.  We have studied your comments carefully and have made corrections which we hope meet with approval. All suggestions and recommendations have been adopted, and the introduced changes are listed in the responses to the review. 

Reviewer 4 Report

Dear authors,
thank you for work and that you made changes.

Below are a few more comments (for clarity, I copied the original comments with your comment, where additions are needed).               

line 121. Figure 1- better localization within Europe

Resp.: We rather suggest to show detailed location of sampling points in the transboundary region. Positioning the locations in Europe would cost resolution of the map.

You can insert a smaller map of Europe in the corner of this map. for many readers, it will be clear where the subscription locations are.

line 152. Please indicate the amount of org. matter added per ha (pot). I do not understand when comparing the effect of organic matter, why it is always added according to the N content. Can you explain it please?

Resp.: The amount of EOMs added to the pot did not exceed 25 g (25 g in case of digestate, 17 g in case compost and 3.3 g for animal meal. We designed the rates of EOMs based on amount of N to be applied. Therefore the total amount of EOMs or amount of added organic matter were different. The goal of the study was to assess impact of various N forms and sources on its dynamics in soil plus effect of N source on crop yields. We wanted to test how mineral N fertilization can be replaced with its organic sources. To be able to evaluate this we had to provide similar amounts of N in soil amendments. Besides this, agricultural good practice in applying organic fertilizers refers to rate of N. Organic matter itself does not generate risks, as opposite to N excessive amounts. If we performed a study on water retention we would have applied EOMs on OM basis. We believe that in a study aimed at N dynamics, referring to N rate was appropriate. Applying the same OM amounts would result in dramatically different N rates between combinations, that would not allow to reach the study objectives.

Can the 8 times more addition of organic matter (digestate x animal meal) be the reason for the changes between variants?

line 156- how many kg of soil is in 1 pot? In each variant the amount of soil was the same and the addition of org. matter was different?

Resp.: It was 3.5 kg of soil in each pot. Yes, in each variant weight of soil was the same. The volume of EOM was different for each EOM. We reflected the situation existing in practice – when EOMs are applied in the field the overall volume of sol is increased. More details on the pot experiment were added to the text.

About pot experiment- you wrote 10 weeks x 4 months-what is correct? Day x night time was the same (12 x 12 hours)? How many luxes were set in the greenhouse?

line 219. I do not find this display useful - what was the standard deviation value of the control? Much more better is that control is one variant of experiment with SD.

Resp.: The control value has been added to the charts as a one of the variable.

In figure 2, you must write control variant to the legend.

Thank you and looking forward to your feedback.

Author Response

We would like to thank you for comments and suggestions, which contributed very much to improve our manuscript.  We have studied your comments carefully and have made corrections which we hope meet with approval. All suggestions and recommendations have been adopted, and the introduced changes are listed in the responses to the review. 

Dear authors,
thank you for work and that you made changes.

Below are a few more comments (for clarity, I copied the original comments with your comment, where additions are needed).               

 line 121. Figure 1- better localization within Europe

Resp.: We rather suggest to show detailed location of sampling points in the transboundary region. Positioning the locations in Europe would cost resolution of the map.

You can insert a smaller map of Europe in the corner of this map. for many readers, it will be clear where the subscription locations are.

Resp 2. The map of Europe has been added to the Figure 1.

line 152. Please indicate the amount of org. matter added per ha (pot). I do not understand when comparing the effect of organic matter, why it is always added according to the N content. Can you explain it please?

Resp.: The amount of EOMs added to the pot did not exceed 25 g (25 g in case of digestate, 17 g in case compost and 3.3 g for animal meal. We designed the rates of EOMs based on amount of N to be applied. Therefore the total amount of EOMs or amount of added organic matter were different. The goal of the study was to assess impact of various N forms and sources on its dynamics in soil plus effect of N source on crop yields. We wanted to test how mineral N fertilization can be replaced with its organic sources. To be able to evaluate this we had to provide similar amounts of N in soil amendments. Besides this, agricultural good practice in applying organic fertilizers refers to rate of N. Organic matter itself does not generate risks, as opposite to N excessive amounts. If we performed a study on water retention we would have applied EOMs on OM basis. We believe that in a study aimed at N dynamics, referring to N rate was appropriate. Applying the same OM amounts would result in dramatically different N rates between combinations, that would not allow to reach the study objectives.

Can the 8 times more addition of organic matter (digestate x animal meal) be the reason for the changes between variants?

Resp 2. We do not expect any substantial impact of different OM volume applied on N fluxes since the amount of N was the same and C/N was not too much different. Different OM inputs could have some impact on water retention of soil but we counteracted this through precise maintaining soil moisture at the level optimal for plants. Another difference in plant growing conditions, resulting from different OM amounts, can be in physical conditions of root growth. But this did not have substantial impact in our study since the total amounts of soil amendments were not high and soils were not compacted in pots.

line 156- how many kg of soil is in 1 pot? In each variant the amount of soil was the same and the addition of org. matter was different?

Resp.: It was 3.5 kg of soil in each pot. Yes, in each variant weight of soil was the same. The volume of EOM was different for each EOM. We reflected the situation existing in practice – when EOMs are applied in the field the overall volume of sol is increased. More details on the pot experiment were added to the text.

About pot experiment- you wrote 10 weeks x 4 months-what is correct? Day x night time was the same (12 x 12 hours)? How many luxes were set in the greenhouse?

Resp 2. Day/night length was set at 16/8 hours. 10 weeks was a mistake. In fact the study was run for 5 months – 4 weeks to enable reaction of amendments with soil and then 4 months of plant growth from seeding to harvest. The text has been corrected. Unfortunately we do not have information on luxes, usually it is not described in articles, however the facility was equipped with supplemental light enabling full range of light.

line 219. I do not find this display useful - what was the standard deviation value of the control? Much more better is that control is one variant of experiment with SD.

Resp.: The control value has been added to the charts as a one of the variable.

In figure 2, you must write control variant to the legend.

 Resp 2. All charts were properly adjusted.